First of all, you must correct the level of the guide rail! Then do the following:

1) Grind a standard bar, which is about 50X250. One end of the rod extends out of the flange (matched with the flange of the lathe spindle).

2) Remove the lathe chuck, install the ground standard rod, and calibrate the near end and the far end respectively, with the coaxiality less than 1C and the same direction.

3) Install a dial indicator on the carriage, which refers to the normal bus and side bus of the standard pole respectively, and find out the error.

4) Generally speaking, adjust the main bus (scrape or cushion the front of the car) first, and then adjust the side bus, and the error will be eliminated after correction.

5) After the overhaul, the machine tool should not only adjust the level of the guide rail according to 300 sections, but also correct the positive bus and side bus of the front, and finally adjust the alignment of the tailstock, so as to complete the main overhaul work.